In constructing walls for buildings and houses of reinforced concrete or of concrete blocks, it is common practice to provide furring strips on the surface of the wall body and a wallboard is placed thereupon to form a lathing. This furring strip method involves considerable skill and time in order to achieve a uniform lathing surface, and when the wall is made of roughly finished concrete with irregular surface, it is necessary to coat the wall with mortar to prepare the flush surface before placing furring strips. When the construction budget does not allow a mortar finish, it is necessary to interpose wooden strips and the like having a suitable thickness between the wall and the furring strips to correct the irregular surface. Unless a certain measure or other is taken to obtain a flush surface, the conventional method is now no longer very appropriate in view of the situation prevailing today in the construction industry which calls for shorter construction terms, simpler work procedures and less cost. Moreover, as the demand for energy saving is having a great impact on the architectural field, a growing number of buildings and houses employ foaming plastics for insulation and for improving their air conditioning efficiency. As for insulation of walls, methods are known to interpose an insulating board made of foaming plastics such as foaming styrol at the time of wallboard lining or to form an insulating layer on the spot after the wallboard is lined by injecting foaming plastics such an foaming uria resin and the like from openings perforated on the wallboard at desired places. The latter method which facilitates injection of insulating material on the spot is more preferred these days as compared with the former method which involves cutting of insulating boards to match the interval of the furring strips and which entails storage of bulky insulating material and transporting the same to the construction spot. Even the latter on-the-spot foaming and filling method can not be considered perfect so long as the lathing is constructed by the conventional furring strip method. In the lathing of the conventional furring strip method, the wall body and the wallboard are continuously connected by flurring strips that are provided vertically and horizontally, so that even if the foaming plastics is filled in the interval between the wall and the wallboard, the insulating layer will not be formed where the furring strips are provided. Also, the insulating material will not be perfectly filled at the junctions of vertical and horizontal furring strips which remain as voids without insulation, whereby the insulation of the wall at such portions becomes imperfect and may cause linear or partial dew condensation which may cause discolorings and soilings of the wall.